According to this stats page, for all extensions imported from svn.wikimedia.org, the most active committers are translatewiki.net (TWN) staff members, usually Siebrand or Raymond. This is because they used to handle the committing of i18n changes from TWN -- which is nowadays handled by l10n-bot, and I understand that l10n-bot is filtered out from all the appropriate statistics.

It would be nice to have these semi-automated i18n commits (the ones where the log message is something like "Localisation updates for") filtered out from this stats page.